Additive manufacturing (AM) or additive printing processes generally involve the buildup of one or more materials to make a net or near net shape (NNS) object, in contrast to subtractive manufacturing methods. Though “additive manufacturing” is an industry standard term (ASTM F2792), AM encompasses various manufacturing and prototyping techniques known under a variety of names, including freeform fabrication, 3D printing, rapid prototyping/tooling, etc. AM techniques are capable of fabricating complex components from a wide variety of materials. Generally, a freestanding object can be fabricated from a 3D model, such as a computer aided design (CAD) model. A particular type of AM process uses electromagnetic radiation such as a laser beam, to solidify or cure a liquid photopolymer, creating a solid three-dimensional object.
Processes such as direct metal laser melting (DMLM), selective laser melting (SLM), and digital light processing (DLP) have been used to produce objects for a variety of industries. A schematic of conventional computer-aided design (CAD)-assisted additive printing is shown in FIG. 1. A single CAD file 101 is processed by a computer 102, which directs or controls printing of the object defined in the CAD file 101 by printing machine 103. The object may be fabricated or manufactured one layer at a time, in either a top-down or bottom-up fashion, depending on the specific apparatus and/or method used. For example, as described in U.S. Pat. No. 5,184,507, a stereolithography system will typically form a three-dimensional part in accordance with a corresponding object representation, which representation may be formed in a CAD system or the like. Before such a representation can be used, however, it must be sliced into a plurality of layer representations. The stereolithography system will then, in the course of building up the object in a stepwise layer-by-layer manner, selectively expose the untransformed layers of material in accordance with the layer representations to form the object layers, and thus, the object itself. The larger or more complex the object to be built, the longer this process will generally take; accordingly, such processes can become unacceptably long for manufacturing large objects. Thus, it is desirable to expedite additive manufacturing.